[libcamera-devel] [PATCH v2 4/7] libcamera: v4l2_controls: Construct from a list of ids

[Jacopo Mondi]

Add a constructor for the V4L2ControlList class that accepts a list of
V4L2 control IDs (V4L2_CID_*). The constructor returns a V4L2ControlList
instance to be used for reading controls only.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/include/v4l2_controls.h |  3 +++
 src/libcamera/v4l2_controls.cpp       | 17 +++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/libcamera/include/v4l2_controls.h b/src/libcamera/include/v4l2_controls.h
index 10b726504951..86c84e06d741 100644
--- a/src/libcamera/include/v4l2_controls.h
+++ b/src/libcamera/include/v4l2_controls.h
@@ -65,6 +65,9 @@ public:
 	using iterator = std::vector<V4L2Control>::iterator;
 	using const_iterator = std::vector<V4L2Control>::const_iterator;
 
+	V4L2ControlList() {}
+	V4L2ControlList(std::vector<unsigned int> ids);
+
 	iterator begin() { return controls_.begin(); }
 	const_iterator begin() const { return controls_.begin(); }
 	iterator end() { return controls_.end(); }
diff --git a/src/libcamera/v4l2_controls.cpp b/src/libcamera/v4l2_controls.cpp
index 84258d9954d0..eeb325cbfff9 100644
--- a/src/libcamera/v4l2_controls.cpp
+++ b/src/libcamera/v4l2_controls.cpp
@@ -202,6 +202,23 @@ V4L2ControlInfo::V4L2ControlInfo(const struct v4l2_query_ext_ctrl &ctrl)
  * and prepare to be re-used for a new control write/read sequence.
  */
 
+/**
+ * \brief Construct a V4L2ControlList from a list of V4L2 controls identifiers
+ * \param ids A list of V4L2 control identifiers (V4L2_CID_*)
+ *
+ * Construct a V4L2ControlList from a list of control identifiers without any
+ * value associated. This constructor is particularly useful to create a
+ * V4L2ControlList that is used to read the values of all controls in the
+ * \a ids list. The created V4L2ControlList should not be used to write control
+ * values unless it is cleared first and then controls with an associated value
+ * are manually added to it.
+ */
+V4L2ControlList::V4L2ControlList(std::vector<unsigned int> ids)
+{
+	for (auto id : ids)
+		add(id);
+}
+
 /**
  * \typedef V4L2ControlList::iterator
  * \brief Iterator on the V4L2 controls contained in the instance
-- 
2.23.0